It has been long known that cellulose ethers, such as carboxymethylcellulose and methylcellulose are effective bulk laxatives. The cellulose ethers relieve constipation by increasing the bulk of the stool, increasing the water content of the stool, and it is believed, by a lubricating effect on the stool.
Previously, cellulose ethers have been administered as bulk laxatives in the form of tablets, powders and suspensions in highly concentrated sugar solutions. Each of these methods of administration has significant disadvantages which have limited the acceptance of these products by consumers.
Tableted cellulose ethers, for example, do not readily dissolve in the digestive tract because these cellulose ethers are highly hygroscopic. The outer portion of the tabIet quickly forms a gel-like hydrate which prevents break up of the tablet and greatly retards hydration of the interior portions of the tablet. Accordingly, the tablet is often excreted as an intact soft gel mass. Although some laxative effect is produced by such gel masses, the cellulose ether is most effective when dispersed uniformly throughout the stool. Thus, when employed in tablet form, cellulose ethers have reduced efficacy as bulk laxatives.
Cellulose ethers have also been administered orally as powders. Such powders often exhibit the same type of gelation as tablets, i e , the individual particles lump together and remain partially undissolved as they pass through the digestive tract. Moreover, administration of cellulose ethers in powdery form has caused nausea, cramping and vomiting in some patients Accordingly, cellulose ethers are not advantageously administered in powder form.
Cellulose ethers have also been administered as bulk laxatives as suspensions of the cellulose ether in water containing high concentrations of sucrose or other sugars and a flavoring. The sugar competes with the cellulose ether for the available water, thereby preventing the cellulose ether from hydratinq sufficiently to form gels. administration of cellulose ethers in such form has the advantage that the cellulose ether is sufficiently dispersed that it does not form significant amounts of lumps in the digestive tract. Unfortunately, however, such suspensions are very thick and semi-gelatinous. As such, the are visually unappealing. More significantly, due to their slimy mouth feel and extreme sweetness, such suspensions are quite unpalatable. Accordingly, such cellulose ether suspensions have not gained significant consumer acceptance
Accordingly, it would be desirable to provide a cellulose ether composition useful as a bulk laxative, which composition is palatable and not visually displeasing and which is administered without the formation of significant amounts of lumps or gels. This can be readily accomplished by adding water or another aqueous liquid to a dry powder mix of a water-soluble cellulose ether and a dispersing/sweetening component, typically sugar. This technology is already known in the prior art, for example, South African Pat. No. 84 1044, published Sept. 26, 1984.
These compositions, however, are not entirely acceptable because a single dose will typically have about 400 calories of nutritive value primarily due to the high sugar content. Such high caloric value is a detracting feature to the average consumer and is unacceptable in users suffering from blood sugar disorders, including diabetics. This is all the more unacceptable because the elderly, who commonly suffer from constipation and are frequent users of laxatives, also commonly exhibit a variety of blood sugar disorders which are aggravated by the consumption of large quantities of sugar.
The caloric content of these compositions can be reduced if, instead of adding granulated sugar to the cellulose ether laxative composition, the sugar is instead used to form a crust around the individual cellulose ether granules. Sugar encrusted cellulose ether particles provide for a product which is readily dispersible in cold aqueous liquids and which result in laxative compositions having substantially less sugar content and less caloric value.
Applicants first prepared the sucrose encrusted cellulose ether particles by dry mixing sugar and cellulose ether, subsequently wet granulating with a small amount of water, and finally drying the wet mixture. Encrusted cellulose ether particles prepared in this way in small laboratory batches are indeed readily dispersible in cold aqueous liquids. However, encrusted particles prepared in this way suffer serious limitations when prepared in large quantities at high speeds using high-tech, production scale equipment. For example, Applicants discovered that the agitation of these particles in a fluid bed dryer apparently destroyed the sugar encrustation and resulted in an end product which would not disperse in cold aqueous liquids. Moreover, when these encrusted particles were milled in a production scale, high-speed mill, the high sugar content "blinded" the milling screen and prevented efficient operation.
Applicants discovered that if, instead of adding water to a dry mixture of sugar and cellulose ether, hot concentrated sugar syrup was added to dry, powdered cellulose ether, a sugar encrusted cellulose ether particle resulted which caused no processing difficulties on production scale equipment and which readily dispersed in cold aqueous fluids.